Massilia rhizosphaerae sp. nov., a rice-associated rhizobacterium with antibacterial activity against Ralstonia solanacearum

Abstract

A novel rhizobacterium, designated strain NEAU-GH312^T, with antibacterial activity against <i>Ralstonia solanacearum</i> was isolated from rhizosphere soil of rice (Heilongjiang Province, PR China) and characterized with a polyphasic approach. Cells of strain NEAU-GH312^T were Gram-stain-negative, aerobic, non-spore-forming, motile with peritrichous flagella and rod-shaped. Colonies were light orange, convex and semi-translucent on Reasoner's 2A (R2A) agar after 2 days of incubation at 28 °C. Growth was observed on R2A agar at 10-40 °C, pH 4.0-8.0 and with 0-5 % (w/v) NaCl. The respiratory quinone was ubiquinone Q-8. The major cellular fatty acids of strain NEAU-GH312^T were C_{16 : 1} <i> ω</i>7<i>c</i> and/or C_{16 : 1} <i> ω</i>6<i>c</i>, C_{16 : 0} and C_{18 : 1} <i> ω</i>7<i>c</i> and/or C_{18 : 1} <i> ω</i>6<i>c</i>. The main polar lipids were phosphatidylglycerol, phosphatidylethanolamine and diphosphatidylglycerol. Phylogenetic analyses confirmed the well-supported affiliation of strain NEAU-GH312^T within the genus <i>Massilia</i>, close to the type strains of <i>Massilia arvi</i> THG-RS2O^T (98.7 %), <i>Massilia norwichensis</i> NS9^T (98.7 %) and <i>Massilia kyonggiensis</i> TSA1^T (98.6 %). Strain NEAU-GH312^T had a genome size of 6.68 Mb and an average DNA G+C content of 66.3 mol%. Based on the genotypic, phenotypic and chemotaxonomic data obtained in this study, strain NEAU-GH312^T could be classified as representative of a novel species of the genus <i>Massilia</i>, for which the name <i>Massilia rhizosphaerae</i> sp. nov. is proposed, with strain NEAU-GH312^T (=DSM 109722^T=CCTCC AB 2019142^T) as the type strain.